import calendar
import datetime

from django.contrib.auth.mixins import PermissionRequiredMixin
from django.core.exceptions import BadRequest
from django.core.paginator import Page
from django.db.models import Count, F, FloatField, Window
from django.db.models.functions import Lead, Trunc
from django.urls import path, reverse_lazy
from django.utils.text import slugify
from django.views.generic.list import ListView

import django_filters
import django_tables2 as tables
from django_filters.views import BaseFilterView
from django_tables2 import SingleTableMixin
from django_tables2.export.views import ExportMixin

from .models import HIDEvent

REPORTS = []


def register_report(cls: "BaseAccessReport"):
    REPORTS.append(cls)
    return cls


class DateTimeFilters(django_filters.FilterSet):
    timestamp = django_filters.DateFromToRangeFilter()


class BaseAccessReport(
    BaseFilterView, ExportMixin, SingleTableMixin, PermissionRequiredMixin, ListView
):
    model = HIDEvent
    permission_required = "doorcontrol.view_hidevent"
    paginate_by = 20
    context_object_name = "object_list"
    template_name = "doorcontrol/access_report.dj.html"

    export_formats = ("csv", "xlsx", "ods")

    filterset_class = DateTimeFilters

    _report_name = None

    @classmethod
    def _report_types(cls):
        yield [
            cls._report_name,
            reverse_lazy("doorcontrol:" + slugify(cls._report_name)),
        ]

    @classmethod
    def _urlpattern(cls):
        slug = slugify(cls._report_name)
        return path(f"reports/{slug}", cls.as_view(), name=slug)

    @property
    def export_name(self):
        return slugify(self._report_name)

    def _selected_report(self):
        return self._report_name

    def get_paginate_by(self, queryset) -> int:
        if "items_per_page" in self.request.GET:
            return int(self.request.GET.get("items_per_page"))
        return super().get_paginate_by(queryset)

    def get_queryset(self):
        return super().get_queryset().select_related("door")

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context["report_types"] = [
            rt for report in REPORTS for rt in report._report_types()
        ]

        page: Page = context["page_obj"]
        context["paginator_range"] = page.paginator.get_elided_page_range(page.number)
        context["selected_report"] = self._selected_report()
        context["items_per_page"] = self.get_paginate_by(None)

        query_params = self.request.GET.copy()
        if "page" in query_params:
            query_params.pop("page")
        context["query_params"] = query_params.urlencode()

        return context


class UnitTimeTable(tables.Table):
    members = tables.columns.Column()
    members_delta = tables.columns.TemplateColumn(
        "{{ value|floatformat:2}}%", verbose_name="Δ Members"
    )
    access_count = tables.columns.Column()
    access_count_delta = tables.columns.TemplateColumn(
        "{{ value|floatformat:2}}%", verbose_name="Δ Access Count"
    )

    class Meta:
        fields = ("members", "members_delta", "access_count", "access_count_delta")


@register_report
class AccessPerUnitTime(BaseAccessReport):
    table_class = UnitTimeTable
    UNIT_TIMES = ["day", "week", "month", "year"]

    @classmethod
    def _report_types(cls):
        for unit_time in cls.UNIT_TIMES:
            yield (
                "Access per " + unit_time.title(),
                reverse_lazy("doorcontrol:access-per-unit-time", args=[unit_time]),
            )

    @classmethod
    def _urlpattern(cls):
        return path(
            "reports/access-per-<unit_time>",
            cls.as_view(),
            name="access-per-unit-time",
        )

    @property
    def _report_name(self):
        unit_time = self.kwargs["unit_time"]
        return "Access per " + unit_time.title()

    def _selected_report(self) -> str:
        return "Access per " + self.kwargs["unit_time"].title()

    def get_table_kwargs(self):
        unit_time = self.kwargs["unit_time"]
        if unit_time == "week":
            unit_time_column = tables.TemplateColumn(
                verbose_name=unit_time.title(),
                template_code=(
                    "{{ value|date|default:default }} - "
                    "{{ value|add:one_week|date|default:default }}"
                ),
                extra_context={"one_week": datetime.timedelta(weeks=1)},
            )
        else:
            if unit_time == "day":
                date_format = "DATE_FORMAT"
            elif unit_time == "month":
                date_format = "N Y"
            elif unit_time == "year":
                date_format = "Y"

            unit_time_column = tables.DateColumn(
                date_format, verbose_name=unit_time.title()
            )

        return {
            "sequence": ("unit_time", "..."),
            "extra_columns": (("unit_time", unit_time_column),),
        }

    def get_queryset(self):
        unit_time = self.kwargs["unit_time"]
        if unit_time not in self.UNIT_TIMES:
            raise BadRequest("unit time must be one of day, week, month, or year")

        granted_event_types = [
            t for t in HIDEvent.EventType if t.name.startswith("GRANTED_ACCESS")
        ]
        return (
            super()
            .get_queryset()
            .filter(event_type__in=granted_event_types)
            .values(unit_time=Trunc("timestamp", unit_time))
            .annotate(
                members=Count("cardholder_id", distinct=True),
                members_delta=(
                    F("members")
                    / Window(
                        Lead("members"),
                        order_by="-unit_time",
                        output_field=FloatField(),
                    )
                    * 100
                    - 100
                ),
                access_count=Count("cardholder_id"),
                access_count_delta=(
                    F("access_count")
                    / Window(
                        Lead("access_count"),
                        order_by="-unit_time",
                        output_field=FloatField(),
                    )
                    * 100
                    - 100
                ),
            )
            .order_by("-unit_time")
        )


class DeniedAccessTable(tables.Table):
    name = tables.TemplateColumn(
        "{{ record.forename|default:'' }} {{ record.surname|default:'' }}"
    )

    class Meta:
        model = HIDEvent

        fields = (
            "timestamp",
            "door",
            "event_type",
            "name",
            "raw_card_number",
            "decoded_card_number",
        )


@register_report
class DeniedAccess(BaseAccessReport):
    _report_name = "Denied Access"
    table_class = DeniedAccessTable

    def get_queryset(self):
        denied_event_types = [
            t for t in HIDEvent.EventType if t.name.startswith("DENIED_ACCESS")
        ]
        return (
            super()
            .get_queryset()
            .filter(event_type__in=denied_event_types)
            .with_decoded_card_number()
        )


class MostActiveMembersTable(tables.Table):
    cardholder_id = tables.Column()
    name = tables.TemplateColumn(
        "{{ record.forename|default:'' }} {{ record.surname|default:'' }}"
    )
    access_count = tables.Column()


@register_report
class MostActiveMembers(BaseAccessReport):
    _report_name = "Most Active Members"
    table_class = MostActiveMembersTable

    def get_queryset(self):
        return (
            super()
            .get_queryset()
            .values("cardholder_id", "forename", "surname")
            .order_by()
            .annotate(access_count=Count("cardholder_id"))
            .order_by("-access_count")
        )


class BusiestDayOfWeekTable(tables.Table):
    timestamp__week_day = tables.Column("Week Day")
    events = tables.Column()

    def render_timestamp__week_day(self, value):
        return calendar.day_name[(value - 2) % 7]


@register_report
class BusiestDayOfWeek(BaseAccessReport):
    _report_name = "Busiest Day of the Week"
    table_pagination = False
    table_class = BusiestDayOfWeekTable

    def get_queryset(self):
        return (
            super()
            .get_queryset()
            .values("timestamp__week_day")
            .annotate(events=Count("timestamp"))
        )


class BusiestTimeOfDayTable(tables.Table):
    timestamp__hour = tables.TemplateColumn("{{ value }}:00", verbose_name="Hour")
    events = tables.Column()


@register_report
class BusiestTimeOfDay(BaseAccessReport):
    _report_name = "Busiest Time of Day"
    table_pagination = False
    table_class = BusiestTimeOfDayTable

    def get_queryset(self):
        return (
            super()
            .get_queryset()
            .values("timestamp__hour")
            .annotate(events=Count("timestamp"))
        )